This project is concerned with the environment of microbes in host cells and tissues. The specific aims are to characterize the molecular constituents of the granules of neutrophil polymorphonuclear granulocytes and to study their antimicrobial activities including killing and degradation of microbial cells. Mononuclear and macrophage phagocytes will also be studied. Studies will be focused on antimicrobial action at the molecular level and the translocation of granule components during phagocytosis. Special emphasis will be placed on proteolysis, membrane perturbation and oxidative mechanisms. Methods to be used include well established ones for isolation of enriched ultracentrifugal populations of phagocytes, ultracentrifugal isolation of subcellular granules and other organella and resolution of granule constituents by established methods of protein chemistry. Antimicrobial action in vitro will be assayed with parent enterobacteria and their LPS mutants. Other techniques to be used are immunofluorescence, immunoassay and catalytic enzyme assay.